Measuring and testing – Gas analysis – Gas chromatography
Reexamination Certificate
2001-03-07
2004-03-09
Williams, Hezron (Department: 2856)
Measuring and testing
Gas analysis
Gas chromatography
C210S198200, C210S656000, C096S102000
Reexamination Certificate
active
06701774
ABSTRACT:
BACKGROUND OF INVENTION
The present invention generally relates to gas chromatography, and specifically, to parallel gas chromatograph systems that can be integrated or used with parallel reactors for high-throughput (i.e., combinatorial) catalyst screening. The present invention also generally relates to microdetectors, and specifically, to microfabricated thermal conductivity detectors suitable for use in gas chromatography, flow detection, catalyst characterization, and other applications. The invention particularly relates, in a preferred embodiment, to parallel gas chromatograph systems with an array of microdetectors, such as microfabricated thermal conductivity detectors.
Gas chromatography, and in particular, multi-channel gas chromatography is known in the art. See, for example, PCT patent application WO 00/23734 (Daniel Industries, Inc.). Thermal conductivity detectors are also known in the art, and have been routinely used for detection in gas chromatographs—alone, or in combination with other detectors. See, for example, U.S. Pat. No. 4,594,879 to Maeda et al., and Great Britain Patent Specification GB 1,262,529.
Combinatorial (i.e., high-throughput) catalysis is likewise known in the art. See U.S. Pat. No. 5,985,356 to Schultz et al., U.S. Pat. No. 6,004,617 to Schultz et al., U.S. Pat. No. 6,030,917 to Weinberg et al., U.S. Pat. No. 5,959,297 to Weinberg et al., U.S. Pat. No. 6,063,633 to Wilson, U.S. Pat. No. 6,149,882 to Guan et al., and PCT applications WO 99/64160, WO 99/51980, WO 00/09255, WO 00/23921, WO 00/32308 and WO 00/51720 each of which patents and applications relates to various aspects of combinatorial materials science and combinatorial catalysis, and each of which (including corresponding US applications from which priority is claimed) is hereby incorporated by reference for all purposes.
Despite the considerable development in the art of gas chromatography to date, there remains a need for improved gas chromatographs to facilitate, among other applications, high-throughput screening of catalysts in parallel fashion—with simultaneous injection, separation and/or detection in multiple analysis channels. In particular, the current state of the art suffers from relatively bulky packaging, limited interchangeability of component parts, limited operational flexibilty and considerable manufacturing expense. Moreover, existing gas chromatographs are not readily integrated into reaction systems, and especially into smaller-scale reactors such as microreactors, for catalyst screening and/or process optimization.
SUMMARY OF INVENTION
It is therefore an object of the present invention to provide improved gas chromatographs and improved microdetectors for parallel gas chromatography that overcome the deficiencies of the prior art. Specifically, it is an object of the invention to provide a gas chromatograph that is more spatially efficient, provides more operational flexibility, and is more economical to manufacture. It is also an object of the invention to provide gas chromatograph that is suitable for applications with high-throughput screening (e.g. of catalysts), including screening of catalysts using parallel flow reactors or parallel flow microreactors.
Briefly, therefore, included among the several inventions disclosed herein, are arrays of microdetectors, especially thermal conductivity microdetectors, parallel gas chromatographs comprising such microdetector arrays, and parallel catalyst evaluation systems comprising parallel reactors integrated with such parallel gas chromatographs. The present invention also includes highly parallel gas chromatograph systems (e.g. having more than about 8 channels, and preferably more than about 16 channels) having improved thermal control. Additional inventions, including parallel injection blocks (for simultaneous injection and simultaneous vaporization of liquid samples), independently and collectively with parallel injection valves (for parallel injection of gaseous samples to gas chromatography columns) are also disclosed. Inventive methodologies are likewise disclosed herein, including for example, methods for parallel gas chromatography, methods for evaluating libraries of catalyst candidates using such gas chromatography methods, methods for parallel detection of thermal conductivity, and methods for detecting improper injections to gas chromatograph systems.
More specifically, the present invention is directed to a gas chromatograph having four or more analysis channels for simultaneous analysis of four or more fluid samples. The gas chromatograph comprises four or more gas chromatography columns (each comprising an inlet for receiving a gaseous mobile phase that includes a gaseous sample, a separation media effective for separating at least one separated component of the gaseous sample from other components thereof, and an outlet for discharging the separated gaseous sample) and a microdetector array comprising four or more thermal conductivity microdetectors for detecting the thermal conductivity of said at least one separated component of the gaseous sample, said thermal conductivity microdetectors being integral with a substrate or mounted on the substrate. The four or more thermal conductivity microdetectors generally have an inlet port in fluid communication with the outlet of one or more of the gas chromatography columns for receiving a separated gaseous sample, a detection cavity, a thin-film detection filament within the detection cavity for detecting at least one separated component of the separated gaseous sample, and an outlet port for discharging the separated gaseous sample.
The gas chromatographs of the present invention include several variously characterized embodiments. The microdetectors are, in one embodiment, preferably microfabricated microdetectors that are integral with the substrate or with one or more microchip bodies mounted on the substrate. In another embodiment, the microdetectors are thermal conductivity detectors comprising a thin-film detection filament in the detection cavity, where the detection filament has a temperature-dependent resistance. In additional embodiments described in greater detail hereinafter, the microdetectors are bonded to the substrate, or are alternatively detachably mounted on the substrate, preferably as microchip bodies comprising one or more microdetectors
In a particularly preferred embodiment, the gas chromatograph is a six-channel gas chromatograph for simultaneous analysis of six or more fluid samples. The gas chromatograph can comprise six or more gas chromatography columns (each of the six or more gas chromatography columns comprising an inlet for receiving a gaseous mobile phase that includes a gaseous sample, a separation media effective for separating at least one component of the sample from other components thereof, and an outlet for discharging the mobile phase and the separated sample) and a microdetector array comprising six or more sample thermal conductivity detectors and at least one reference thermal conductivity detector. Each of the sample and reference thermal conductivity detectors are integral with or mounted on a substrate with a planar density of at least about 1 thermal conductivity detector per 1 cm
2
, and the ratio of sample detectors to reference detector(s) is at least 2:1. Each of the six or more sample thermal conductivity detectors comprises an inlet port in fluid communication with the outlet of one of the gas chromatography columns for receiving a separated sample, a detection cavity having a volume ranging from about 1 &mgr;l to about 500 &mgr;l for detecting at least one component of the separated sample, a thin-film detection filament within the detection cavity, the detection filament having a temperature-dependent resistance, an outlet port for discharging the sample, a first conductive path between the a first end of the detection filament and a first electrical contact, and a second conductive path between a second end of the detection filament and a second electrical contact. The first and second electr
Bergh H. Sam
Engstrom James R.
Guan Shenheng
Myslovaty Michael
Pinkas Daniel Meron
Politzer Jay L
Senniger Powers Leavitt & Roedel
Symyx Technologies Inc.
Williams Hezron
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